Priority services is the name given to preferred treatment of certain kinds of traffic (e.g., media/data and signaling) over other kinds of traffic in, for example, the context of civilian or defense communications networks.
Priority in a public switched telephone network (PSTN) is performed on a switch by switch basis. Calls for priority users such as governments pass through the switches while non-priority traffic is blocked.
Three kinds of priority services exist at present; namely, wireless priority service (WPS), Government emergency telecommunications service (GETS) by national communications system (NCS) and multi-level precedents preemption (MLPP) by the United States Department of Defense (DOD).
GETS provides an ability to preempt calls at a lower priority than MLPP. GETS also provides for buffer-type queuing of a call such that the call will be the first call to pass when a necessary resource becomes available. Call control functionality includes the decision of choosing which call to allow and which call to preempt. Resource control and policy-based management functionality includes the decision of when to preempt a call or when to buffer-type queue a call.
Within the context of voice, video and other data communications (e.g., multimedia communications and the like) via packet based networks (e.g., Ethernet, etc.) there is presently no preemption or priority handling of voice calls or multimedia services.